Unknown Technology in Nanotechnology

New Nanotechnology Invention :

1. Carbon Nanotubes hold Long-sought battery
2. Nanodevices bend under the Forces of light
3. Artificial gecko feet using carbon nanotubes
4. No Need to clean Nanoclothes
Read more to view details of above topics


Carbon Nanotubes hold Long-sought battery:

The rechargeable lithium-ion batteries now so common in everything from iPods to hybrid cars can store twice the energy of similarly sized nickel-metal hydride batteries and up to six times as much as their lead-acid progenitors.


But these advances are only a small evolutionary step from the world’s first battery designed by Alessandro Volta in 1800 using layers of metal and blotting paper soaked in salt water.

With battery technology advances long overdue, researchers are racing to develop more efficient ways to store power.

One hopeful option is in the use of carbon nanotubes, which can store much more electricity by weight than lithium-ion batteries while keeping their charge and remain durable for far longer.

But what are carbon nanotubes, and how can they be used to store energy? Technicians skilled in working with matter at the molecular (nano) level can arrange pure carbon molecules in cylindrical structures that are both strong and flexible.

They have significantly higher energy density and can store more electricity than any currently available technology. These tubes, each only billionths of a meter wide, essentially become highly efficient, electrically conductive pipes for storing and providing power.

Electrical engineers at the Massachusetts Institute of Technology (MIT) have formed carbon molecules into tiny springs that store as much electricity as same sized lithium-ion batteries but can maintain a charge while dormant for years and work well in temperature extremes.

Stanford University researchers have created ink made from carbon nanotubes that can be drawn onto paper where it serves as a high-capacity rechargeable energy storage medium.
And University of Maryland scientists have created nanostructures able to store and transport power at 10 times the energy density of lithium-ion batteries.

The accelerating growth of nanotechnology itself, which has not yet been thoroughly tested to evaluate potential down sides, has some health advocates worried.

Animal studies have shown that some nanoparticles, if inhaled or ingested, can harm the lungs and also cross the blood-brain barrier, which protects the brain from toxins in the bloodstream.

There are fuel cells created in 1839 but only recently commercialized. Not batteries per set, fuel cells generate, store and dispense power by forcing a reaction between a fuel (hydrogen from water, methanol) and oxygen, creating usable non-polluting electricity.

One major hurdle for fuel cell makers is making them small enough to be able to work in laptops and other small personal electronics.

Nanodevices bend under the Forces of light:

A team of researchers has fabricated a micron-scale device that deforms significantly under the force of light, a technology that could form the basis for tiny light-actuated switches or filters in future optical devices.

In recent years several groups have engineered novel structures on scales so small that the force of light passing through them actually wields an appreciable force

In recent years several groups have engineered novel structures on scales so small that the force of light passing through them actually wields an appreciable force.

The devices harness the so-called gradient optical force, by which a light beam can exert a push or pull in a direction transverse, or perpendicular, to the direction of the light's propagation.

In a recent example, outlined in Nature last year by a team from Yale University and the University of Washington in Seattle, laser light routed through a tiny bridge-shaped resonator induced the bridge to vibrate up and down within a range of a few
nanometers. (Scientific American is part of the Nature Publishing Group.)

"A lot of groups are starting to learn how to vibrate structures using light," says Cornell physicist Michal Lipson, a study co-author and the leader of the nanophotonics group.

"But what we decided to do is instead of just vibrate, to really control the structure—to bend or move the structure—and keep it static just like that."

Running low-power laser light, akin to that from a typical laser pointer, through the rings generates a tunable response—either attractive or repulsive, depending on the wavelength—that changed the size of the gap between the rings by as much as 20 nanometers. (A nanometer is one billionth of a meter.)

By modulating the intensity of the laser light, Lipson says, the gap can be opened or closed to varying widths.

"You can completely control the amount of bending with the amount of incident power that you have," she says. Such controlled deformation could be used to form tiny switches driven by light rather than electricity.

Hong Tang, an assistant professor of electrical engineering at Yale who co-authored last year's nanobridge paper in Nature, sees these devices possibly forming the basis for tunable optical filters.

By using a laser to induce movements that change a structure's resonance, he explains, the passage of light from another source—say, an optical communication channel—can be controlled.

Tang calls the new application of the gradient force "very innovative." He points out that the ring structure, which Lipson says is designed for both low mass and malleability, harnesses the optical force on a greater scale than the smaller vibrating beam did.

"There are different field applications, and there is a trade-off," Tang says. "We pushed the limit to small, and they pushed the limit to large displacement."

"The displacement demonstrated in this device is 20 nanometers, which is really significant," Tang says. "This is really a big change for the optical force–induced displacement."

Artificial gecko feet using carbon nanotubes:

Liming Dai, a professor at the University of Dayton, and Zhong Wang, director of the Center for Nanostructure Characterization at Georgia tech, have developed a new adhesive that closely mimics the structures on gecko feet.

Gecko feet are covered with millions of micro-scale hairs which branch into even smaller hairs. The hairs each have a weak electrical interaction with a surface, and add up to a strong force over the area of the foot.

The researches came up with an adhesive made of carbon nanotubes whose structure closely resembles that of gecko feet. The material is 10 times more adhesive than the geckos’ feet and it’s easy to lift back up.

One problem with these materials is that when the material gets dirty they don’t work well. No one has been able to do that.

Dai says that carbon nanotubes’ versatility may help overcome the dirt problem. Dai is developing adhesive nanotube arrays that have the nanotubes coated with proteins that change their shape in response to temperature changes.

The idea is that robot feet could heat up when they get clogged, sloughing off the dirt so that it can keep walking.

No Need to clean Nanoclothes :

Researchers at Monash University, in Victoria, Australia, led by organic chemist and nanomaterials researcher Walid Daoud, have discovered a way to coat fibers with titanium dioxide nanocrystals, which break down food and dirt in sunlight.

They have coated natural fibers such as wool, silk, and hemp so that they will automatically shed food, grime, and even red-wine stains when exposed to sunlight.

These nanocrystals cannot decompose wool and are harmless to skin. The nanocrystal coating doesn’t change the look or feel of the material.

Titanium dioxide also destroys bacteria in the presence of sunlight by breaking down the cell walls of the microorganisms. Self-cleaning fabrics would be useful in hospitals and other medical settings.

The material stands up to red-wine stains, which are very difficult to remove. After 20 hours of exposure to simulated sunlight, titanium-dioxide-coated wool shows almost no sign of the red stain, while the untreated wool remains boldly stained.

Other stains disappear faster: coffee stains fade away in two hours, while blue-ink stains disappear in seventeen hours.

Stain-repellant fabrics and paints that are currently on the market typically have a nanoparticle or nanofiber coating that causes drops of liquid to roll off instead of getting absorbed into the material, taking small particles of dirt and grime with them.